JP5941858B2 - Auto tensioner - Google Patents

Description

  The present invention relates to an auto tensioner that adjusts the tension of a transmission belt.

  As a device that adjusts the tension of the transmission belt in an automotive accessory drive system, etc., a fixed member that is fixed around the pivot and a pulley that is supported rotatably around the pivot and around which the belt is wound are attached. A possible rotating member and one end locked to the fixed member and the other end locked to the rotating member to rotate the rotating member in one direction around the pivot with respect to the fixed member. An auto tensioner having a coil spring that is urged to move is often used.

  In this auto tensioner, a pressure receiving cylindrical portion extending in the axial direction of the pivot is formed on one of the fixed member and the rotating member on the inner peripheral side or outer peripheral side of the coil spring, and the coil spring is formed along the peripheral surface of the pressure receiving cylindrical portion. An elastic body extending in an arc shape on the inner or outer peripheral side of the elastic member, and friction that is located on the inner side or the outer side in the radial direction of the elastic body and is pressed against the peripheral surface of the pressure-receiving cylindrical portion by the diameter reduction or expansion There is a member provided with a member to give damping to the rotation of the rotation member (for example, see Patent Documents 1-4).

  In this type of auto tensioner, the circumferential surface of the friction member and the pressure-receiving cylindrical portion is divided depending on whether the rotating member rotates in the belt slack direction that lowers the belt tension or in the belt tension direction that increases the belt tension. The frictional force generated between the rotating member and the rotating member can be made to have an asymmetric damping characteristic. That is, by increasing the frictional force in the belt slack direction and increasing the damping, string vibration due to a sudden drop in the tension of the transmission belt can be prevented, and in the belt tensioning direction, the frictional force is reduced and the damping is weakened. As a result, the reduced tension of the transmission belt can be quickly recovered.

  In each of Patent Documents 1 and 2, a pressure receiving cylindrical portion is formed on the inner peripheral side of the coil spring, and a friction member is pressed, and an arc-shaped portion extending along the outer peripheral surface of the pressure receiving cylindrical portion. A reduced-diameter type damping method is adopted in which the elastic body is reduced in diameter and the friction member is pressed against the outer peripheral surface of the pressure-receiving cylindrical portion. In addition, what was described in patent document 1 makes an elastic body also serve as a friction member, presses the elastic body against the outer peripheral surface of the pressure-receiving cylindrical portion by the reduced diameter of the coil spring, and also includes a fixed member and a rotating member. A housing portion that overlaps the inside and the outside is formed on both of them, and an elastic sleeve is housed in the housing portion, and the damping force between the fixed member and the rotating member is increased by utilizing the compressive deformation of the elastic sleeve.

  On the other hand, all of those described in Patent Documents 3 and 4 form a pressure-receiving cylindrical portion on which the friction member is pressed on the outer peripheral side of the coil spring and extend along the inner peripheral surface of the pressure-receiving cylindrical portion. The elastic body is expanded in diameter, and a large-diameter type damping method is employed in which the friction member is pressed against the inner peripheral surface of the pressure-receiving cylindrical portion. In the device disclosed in Patent Document 3, the friction member coupled to the elastic body is pressed against the inner peripheral surface of the pressure-receiving cylindrical portion by the outward spring force due to the expansion of the diameter of the coil spring. In addition, in Patent Document 4, an elastic body and a coil spring are connected in series, one of them is locked to a fixed member, and the other is locked to a rotating member. The friction member is pressed against the inner peripheral surface of the pressure-receiving cylindrical portion by the diameter-expanding deformation and the diameter-expanding deformation of the elastic body due to the extension of the coil spring so as to increase the damping force.

  Comparing the above-mentioned reduced-diameter type and enlarged-diameter type damping methods, the reduced-diameter type can be designed compactly because the pressure-receiving cylindrical part that presses the friction member and applies the damping force has a small diameter. There is an advantage that an auto tensioner mounted on an automobile or the like can be reduced in weight. Further, since the small-diameter pressure receiving cylindrical portion pressed from the outer diameter side has high rigidity, it can be made thinner and further lightened.

Japanese Examined Patent Publication No. 62-2182 Japanese Patent No. 3660651 Special table 2009-533619 JP 2006-97889 A

  The auto tensioner having the above-described asymmetric damping characteristic that presses the friction member against the peripheral surface of the pressure-receiving cylindrical portion with the spring force of only the elastic body or only the coil spring may lack the damping force. A combination of the spring force due to the diameter reduction of the coil spring described in Patent Document 1 and the compression deformation of the elastic sleeve, and the spring force and coil spring that expands the diameter of the elastic body itself described in Patent Document 4 What uses it combining with the spring force which expand | extends can fully raise a damping force.

  However, since the auto-tensioner of the reduced diameter type damping system described in Patent Document 1 needs to form an accommodating portion in both the fixing member and the rotating member and accommodate the elastic sleeve in the accommodating portion. There is a problem that the configuration becomes complicated and the cost becomes high. On the other hand, the diameter-enhanced damping type auto-tensioner described in Patent Document 4 has a large pressure-receiving cylindrical part that presses the friction member and becomes heavier. There is. Moreover, since the thing described in patent document 4 has connected the elastic body and the coil spring in series, these spring forces interfere and there also exists a problem that adjustment of damping force is difficult.

  Therefore, an object of the present invention is to provide an auto tensioner that can secure a sufficient damping force with a simple configuration by a reduced diameter type damping system.

  In order to solve the above-described problems, the present invention provides a fixing member that is fixed to rotate around a pivot, and a pivot that is supported so as to be rotatable about the pivot and can be fitted with a pulley around which a belt is wound. One end of the member is locked to the fixed member, the other end is locked to the rotating member, and the rotating member is moved in one direction around the pivot with respect to the fixed member. A coil spring that urges the rotation, and a pressure receiving cylindrical portion that extends in the axial direction about the pivot axis is formed on one of the fixed member and the rotation member on the inner peripheral side of the coil spring, and the pressure receiving cylinder An elastic body extending in an arc shape along the outer peripheral surface of the coil spring on the inner peripheral side of the coil spring, and the outer peripheral surface of the pressure-receiving cylindrical portion located on the radially inner side of the elastic body by the reduced diameter of the elastic body In an auto tensioner provided with a friction member pressed against One end side of the elastic body extending in an arc shape is locked to the other of the fixing member and the rotating member, the other end side is a free end, and an arc shape is formed between the coil spring and the elastic body. A configuration is adopted in which a damping member is provided that extends and presses the friction member against the outer peripheral surface of the pressure-receiving cylindrical portion via the elastic body by the reduced diameter of the coil spring.

  That is, one end side of the elastic body extending in an arc shape is connected to the other of the fixing member and the rotating member, that is, the member that does not form the pressure receiving cylindrical portion of the fixing member and the rotating member (the elastic body locking member). ), The other end is a free end, extends in a circular arc shape between the coil spring and the elastic body, and the friction member is attached to the outer periphery of the pressure-receiving cylindrical portion via the elastic body by the reduced diameter of the coil spring. By providing a damping member that presses against the surface, a sufficient damping force can be ensured with a simple configuration by using the spring force of the elastic body that contracts the diameter and the contraction force of the coil spring. I was able to do it. In this auto tensioner, the spring force of the elastic body and the contraction force of the coil spring act independently as the damping force, so the spring characteristics of the elastic body and the spring characteristics of the coil spring can be individually designed to adjust the damping force. It can be done easily. Further, since the spring force of the coil spring that reduces the diameter is transmitted to the elastic body and the friction member via the damping member, the pressure at which the friction member is pressed against the pressure-receiving cylindrical portion is equalized by adjusting the shape of the damping member. Thus, uneven wear of the friction member can be prevented. Furthermore, the vibration of the coil spring can be attenuated by the damping member, and the resonance of the coil spring due to the forced vibration can also be prevented.

  The material of the damping member is preferably one that can dampen the resonance of the coil spring without being damaged by receiving the spring force of the coil spring. As such a material, the base material is made of polyamide 6 such as polyamide 6, polyamide 66 or polyamide 46, synthetic resin such as polyethylene, polyacetal or polyarylate, and glass fiber, aramid fiber or carbon fiber is dispersed as a reinforcing material. Fiber reinforced plastics reinforced and elastomer materials such as relatively hard rubber and urethane.

  A protruding portion toward the outer diameter side is provided on one end side of the elastic body, and the end portion of the coil spring on the side locked by the other of the fixing member and the rotating member (elastic body locking member) is axially moved. The one end side of the elastic body can be easily locked by sandwiching and locking the protruding portion of the elastic body between the bent portion of the coil spring, the other of the fixing member and the rotating member. can do.

  The damping member is brought into contact with the coil spring within one turn of the spiral coil from the end on the side where the coil spring is locked to the other of the fixing member and the rotation member (elastic body locking member). By making it, it is possible to prevent an increase in the spring constant of the coil spring.

  By providing the damping member with a convex portion projecting to the outer diameter side and fitting the convex portion into a concave portion provided on the other of the fixing member and the rotating member (elastic body locking member), The damping member can be stably held by preventing displacement in the direction.

  The autotensioner according to the present invention has one end side of an elastic body extending in an arc shape locked to an elastic body locking member that does not form a pressure receiving cylindrical portion of a fixed member and a rotating member, A damping member is provided that has a free end as an end, extends in an arc shape between the coil spring and the elastic body, and presses the friction member against the outer peripheral surface of the pressure-receiving cylindrical portion through the elastic body by the reduced diameter of the coil spring. Therefore, a sufficient damping force can be secured with a simple configuration by the reduced diameter type damping method. In this auto tensioner, the spring force of the elastic body and the diameter reducing force of the coil spring act independently as the damping force, so that the damping force can be easily adjusted. In addition, the spring force of the coil spring that reduces the diameter is transmitted to the elastic body and the friction member via the damping member, so that the pressure that the friction member presses against the pressure-receiving cylindrical portion is equalized to prevent uneven wear of the friction member. You can also Furthermore, the vibration of the coil spring can be attenuated by the damping member, and the resonance of the coil spring due to the forced vibration can also be prevented.

1 is a longitudinal sectional view showing an auto tensioner according to a first embodiment. Sectional view along the line II-II in FIG. (A) is a perspective view showing a locking portion at one end of the coil spring of FIG. 2, (b) is a partially omitted perspective view from the back side of (a). A longitudinal sectional view showing an auto tensioner according to a second embodiment. Sectional view along line VV in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 show a first embodiment. As shown in FIGS. 1 and 2, the auto tensioner adjusts the tension of a transmission belt that transmits the power of a crankshaft of an automobile engine to an auxiliary machine, and the rotation is fixed around a pivot member 1. A fixed member 2, a pivot member 3 rotatably supported by the pivot member 1, and a pulley P around which the transmission belt is wound, and one end portion of the fixed member 2 and the other end portion of the pivot member 3. A coil spring 4 is provided that is engaged with the member 3 and urges the rotation member 3 to rotate in one direction around the pivot member 1.

  The rotating member 3 is formed with a pressure receiving cylindrical portion 5 extending in the axial direction of the pivot member 1 on the inner peripheral side of the coil spring 4, and on the inner peripheral side of the coil spring 4 along the outer peripheral surface of the pressure receiving cylindrical portion 5. A metal leaf spring 6 as an elastic body extending in an arc shape, and a friction member 7 that is positioned on the radially inner side of the leaf spring 6 and is pressed against the outer peripheral surface of the pressure-receiving cylindrical portion 5 by the reduced diameter of the leaf spring 6. And are provided. A damping member 8 extending in an arc shape is provided between the coil spring 4 and the leaf spring 6.

  The fixing member 2 includes an inner cylinder part 2a fitted and fixed to the pivot member 1, an outer cylinder part 2b projecting to the outer diameter side of the coil spring 4, and an annular shape connecting the inner cylinder part 2a and the outer cylinder part 2b. And a flange portion 2d attached to an engine block (not shown), and a spiral surface 2e is formed on the step portion of the bottom wall portion 2c along which the coil spring 4 runs. In this embodiment, the rotation of the pivot member 1 and the fixing member 2 is fixed by attaching the flange portion 2d to the engine block.

  The rotating member 3 includes a pressure receiving cylindrical portion 5 that is rotatably supported by the pivot member 1 by a bush 9, an outer cylindrical portion 3 b that projects to the outer diameter side of the coil spring 4, a pressure receiving cylindrical portion 5, and an outer cylinder. An annular bottom wall portion 3c for connecting the portion 3b and a pulley support portion 3d for rotatably supporting the pulley P by the bearing 10 are formed. A spiral surface 3e is formed on the bottom wall portion 3c along the coil spring 4. Yes.

  Both end portions of the outer cylindrical portion 2b of the fixing member 2 and the outer cylindrical portion 3b of the rotating member 3 overlap in the axial direction to form a storage portion for the coil spring 4. A cap 11 that seals the inside is attached to the opening of the pivot member 3 in which the pivot member 1 is fitted.

  2 and 3A, one end of the coil spring 4 is provided with a bent portion 4a in the axial direction, and this bent portion 4a is formed on the bottom wall portion 2c of the fixing member 2. As shown in FIG. It is locked to the wall surface 2g of the circumferential kerf 2f formed on the spiral surface 2e. Further, a bent portion 6a as a protruding portion toward the outer diameter side is provided on one end side of the leaf spring 6, and this bent portion 6a is provided between the bent portion 4a of the coil spring 4 and the wall surface 2g of the cut groove 2f. It is pinched and locked in contact. Although not shown, the other end of the coil spring 4 is fitted and locked in a recess formed on the bottom wall 3c side of the rotating member 3.

  As described above, the leaf spring 6 has the bent portion 6a on one end side sandwiched between the bent portion 4a of the coil spring 4 and the wall surface 2g of the kerf 2f so that the pressure receiving cylindrical portion 5 is not formed. The other end side is a free end, which is locked to the wall surface 2g of the kerf 2f provided in the fixing member 2 serving as a stop member.

  The friction member 7 is a circular arc having a circumferential opening mainly composed of a polyamide 6, polyamide 66, polyamide 46 or other polyamide, a synthetic resin such as polyethylene, polyacetal, polyarylate, or the like, or an elastomer such as rubber or urethane. And attached to the inner peripheral surface of the leaf spring 6. The friction member 7 may be formed by a method in which a molten material is coated on the inner peripheral surface of the leaf spring 6 by application, spraying, or the like, or injection molded using the leaf spring 6 as an insert material. Moreover, you may integrate with the leaf | plate spring 6 by the mechanical coupling | bonding by fitting etc. of a convex part and a recessed part.

  The damping member 8 is made of a base material such as polyamide 6, polyamide 66, polyamide 46, or other synthetic resin, polyethylene, polyacetal, polyarylate, or the like, and as a reinforcing material, glass fiber, aramid fiber, carbon fiber or the like is dispersed. It is made of a reinforced fiber reinforced plastic or an elastomer material such as rubber or urethane having a relatively high hardness.

  As shown in FIGS. 2 and 3B, the damping member 8 contacts the coil spring 4 within one first turn of the helical coil from one end of the coil spring 4 locked to the fixing member 2. In this manner, the spring constant of the coil spring 4 is prevented from increasing by forming it in an arc shape having a circumferential opening. Further, the damping member 8 is provided with a convex portion 8a protruding from the outer peripheral surface, and this convex portion 8a is fitted and locked in a groove 2h as a concave portion provided in the outer cylindrical portion 2b of the fixing member 2. Yes. Therefore, the damping member 8 is stably held without shifting in the circumferential direction.

  The operation of the auto tensioner according to the first embodiment will be described below with reference to FIG. The coil spring 4 is incorporated in a state of being twisted to a predetermined twist angle in advance, and urges the rotating member 3 in the belt tension direction counterclockwise. Further, the leaf spring 6 is expanded and incorporated, and the friction member 7 is pressed against the outer peripheral surface of the pressure-receiving cylindrical portion 5 by a spring force to reduce the diameter.

  When the tension of the transmission belt wound around the pulley P increases, the rotating member 3 rotates in the clockwise belt slack direction against the urging force of the coil spring 4. At this time, the leaf spring 6 in which the bent portion 6a on one end side is locked to the fixing member 2 is moved to the other end side by the clockwise frictional force applied to the friction member 7 from the pressure receiving cylindrical portion 5 of the rotating member 3. Since this is pulled toward the free end, the diameter is reduced, and the damping force that presses the friction member 7 against the pressure-receiving cylindrical portion 5 is increased. At the same time, the coil spring 4 is reduced in diameter, and the spring force due to this reduced diameter is transmitted to the leaf spring 6 and the friction member 7 via the damping member 8, and acts as a damping force that presses the friction member 7 against the pressure-receiving cylindrical portion 5. .

  Therefore, the rotation of the rotating member 3 in the belt slack direction is attenuated by a high damping force, and string vibration due to a sudden drop in tension of the transmission belt can be prevented. Further, since the spring force of the coil spring 4 whose diameter is reduced is transmitted to the leaf spring 6 and the friction member 7 via the damping member 8, the pressure with which the friction member 7 is pressed against the pressure-receiving cylindrical portion 5 is equalized, and the friction force is reduced. Uneven wear of the member 7 can also be prevented. Further, the vibration of the coil spring 4 can be damped by the damping member 8 to prevent resonance of the coil spring 4 due to forced vibration.

  When the tension of the transmission belt decreases, the rotating member 3 rotates in the counterclockwise belt tension direction by the biasing force of the coil spring 4. At this time, the leaf spring 6 in which the bent portion 6a on one end side is locked to the fixing member 2 is compressed in the circumferential direction by the frictional resistance of the friction member 7 with respect to the rotating member 3 that rotates counterclockwise, and the diameter is increased. Thus, the damping force that presses the friction member 7 against the pressure-receiving cylindrical portion 5 is reduced. Therefore, only weak damping acts on the rotation of the rotation member 3 in the belt tension direction, and the tension of the transmission belt can be quickly recovered.

  4 and 5 show a second embodiment. In this auto tensioner, the pressure-receiving cylindrical portion 5 is provided on the fixing member 2, and the bent portion 6 a on one end side of the leaf spring 6 is a rotating member that serves as an elastic body locking member on which the pressure-receiving cylindrical portion 5 is not formed. 3 is basically different from that of the first embodiment. As in the first embodiment, a friction member 7 that is pressed against the outer peripheral surface of the pressure-receiving cylindrical portion 5 is provided on the inner diameter side of the arc-shaped leaf spring 6, and the coil spring 4, the leaf spring 6, and the like. Between them, a damping member 8 extending in an arc shape is provided.

  The fixing member 2 includes a pressure receiving cylindrical portion 5 supported on the pivot member 1 by a bush 9 so as to be relatively rotatable, an outer cylindrical portion 2b projecting to the outer diameter side of the coil spring 4, a pressure receiving cylindrical portion 5 and an outer cylindrical portion. An annular bottom wall portion 2c for connecting 2b and a flange portion 2d attached to an engine block (not shown) are formed, and a spiral surface 2e is formed on the bottom wall portion 2c along which the coil spring 4 runs. In this embodiment, by attaching the flange portion 2d to the engine block, only the fixing member 2 is fixed in rotation, and the pivot member 1 rotates together with the rotation member 3.

  The rotating member 3 connects the inner cylinder part 3a fitted and fixed to the pivot member 1, the outer cylinder part 3b protruding to the outer diameter side of the coil spring 4, and the inner cylinder part 3a and the outer cylinder part 3b. An annular bottom wall portion 3c and a pulley support portion 3d that rotatably supports the pulley P with a bearing 10 are formed, and a spiral surface 3e is formed on the step portion of the bottom wall portion 3c along which the coil spring 4 runs.

  Both the distal end portions of the outer cylindrical portion 2b of the fixing member 2 and the outer cylindrical portion 3b of the rotating member 3 are overlapped in the axial direction to form a storage portion for the coil spring 4 as in the first embodiment. ing. Further, a cap 11 that seals the inside is attached to the opening in which the pivot member 1 of the fixing member 2 is fitted.

  One end portion of the coil spring 4 is provided with a bent portion 4a in the axial direction, and the bent portion 4a is a circumferential kerf formed on the spiral surface 3e of the bottom wall portion 3c of the rotating member 3. A bent portion 6a that is locked to the wall surface 3g of 3f and provided on one end side of the leaf spring 6 is sandwiched and locked in a contact state between the bent portion 4a and the wall surface 3g of the cut groove 3f. Thus, one end side of the leaf spring 6 is locked to the rotating member 3 that is an elastic body locking member on which the pressure receiving cylindrical portion 5 is not formed, and the other end side is a free end. Although not shown, the other end side of the coil spring 4 is fitted and locked in a recess formed on the bottom wall 2c side of the fixing member 2.

  The damping member 8 is formed in an arc shape that comes into contact with the coil spring 4 within one first turn of the spiral coil from one end of the coil spring 4 that is locked to the rotating member 3. Although not shown, the damping member 8 is provided with a convex portion 8a similar to that of the first embodiment, and this convex portion 8a is fitted into a groove provided in the outer cylinder portion 3b of the rotating member 3. Is locked.

  The operation of the auto tensioner according to the second embodiment will be described below based on FIG. Similar to the first embodiment, the coil spring 4 is incorporated in a state of being twisted to a predetermined twist angle, and urges the rotating member 3 in the belt tension direction counterclockwise. Further, the leaf spring 6 is also expanded and incorporated, and the friction member 7 is pressed against the outer peripheral surface of the pressure receiving cylindrical portion 5 by a spring force to reduce the diameter.

  When the tension of the transmission belt increases, the rotating member 3 rotates in the clockwise belt slack direction against the urging force of the coil spring 4. At this time, the leaf spring 6 in which the bent portion 6 a on one end side is locked to the rotating member 3 is moved to the other end side by the clockwise frictional force applied to the friction member 7 from the pressure receiving cylindrical portion 5 of the fixing member 2. Since this is pulled toward the free end, the diameter is reduced, and the damping force that presses the friction member 7 against the pressure-receiving cylindrical portion 5 is increased. At the same time, the coil spring 4 is reduced in diameter, and the spring force due to the reduced diameter presses the friction member 7 against the pressure receiving cylindrical portion 5 via the damping member 8 to further increase the damping force.

  Therefore, also in this embodiment, the rotation of the rotating member 3 in the belt slack direction is attenuated by a high damping force, and string vibration due to a sudden drop in tension of the transmission belt can be prevented. Further, since the spring force of the coil spring 4 whose diameter is reduced is transmitted to the leaf spring 6 and the friction member 7 via the damping member 8, the pressure with which the friction member 7 is pressed against the pressure-receiving cylindrical portion 5 is equalized, and the friction force is reduced. The uneven wear of the member 7 can also be prevented, and the vibration of the coil spring 4 can be attenuated by the damping member 8 to prevent resonance of the coil spring 4 due to forced vibration.

  When the tension of the transmission belt decreases, the rotating member 3 rotates in the counterclockwise belt tension direction by the biasing force of the coil spring 4. At this time, the leaf spring 6 in which the bent portion 6a on one end side is locked to the rotating member 3 is compressed and expanded in the circumferential direction by the frictional resistance of the friction member 7 with respect to the rotating member 3 that rotates counterclockwise. Since the diameter is increased, the damping force for pressing the friction member 7 against the pressure-receiving cylindrical portion 5 is reduced. Therefore, only weak damping acts on the rotation of the rotation member 3 in the belt tension direction, and the tension of the transmission belt can be quickly recovered.

  In each of the above-described embodiments, the leaf spring is incorporated in an expanded state, but the leaf spring may be incorporated in a natural state where the diameter is not expanded. In this case, the diameter is reduced only when the rotating member is rotated in the belt slack direction, and the friction member is pressed against the pressure receiving cylindrical portion.

  In each of the embodiments described above, the elastic body is a metal leaf spring, and a bent portion for locking is formed on one end side thereof, but the elastic body can also be a synthetic resin arcuate sleeve, etc. A protruding portion, a bulging portion, or the like can be formed and locked on one end side.

  In each of the above-described embodiments, the tension of the transmission belt that transmits the power of the crankshaft of the automobile engine to the auxiliary machine is adjusted. However, the auto tensioner according to the present invention has the tension of the transmission belt of another belt transmission mechanism. It can also be used for adjusting the angle.

P Pulley 1 Pivot member 2 Fixing member 2a Inner tube portion 2b Outer tube portion 2c Bottom wall portion 2d Flange portion 2e Spiral surface 2f Groove 2g Wall surface 2h Groove 3 Rotating member 3a Inner tube portion 3b Outer tube portion 3c Bottom wall portion 3d Pulley support portion 3e Spiral surface 3f Cut groove 3g Wall surface 4 Coil spring 4a Bending portion 5 Pressure receiving cylindrical portion 6 Plate spring 6a Bending portion 7 Friction member 8 Damping member 8a Protruding portion 9 Bush 10 Bearing 11 Cap

Claims (4)

A fixed member whose rotation is fixed around the pivot axis;
A rotating member that is rotatably supported around the pivot and is capable of attaching a pulley around which a belt is wound;
One end is locked to the fixed member, the other end is locked to the rotating member, and the rotating member is rotated in one direction around the pivot with respect to the fixed member. A coil spring for energizing,
On one of the fixing member and the rotating member, a pressure receiving cylindrical portion extending in the axial direction around the pivot axis is formed on the inner peripheral side of the coil spring,
An elastic body extending in an arc shape on the inner peripheral side of the coil spring along the outer peripheral surface of the pressure-receiving cylindrical section, and located on the radially inner side of the elastic body, and the pressure-receiving cylindrical section by the reduced diameter of the elastic body In an auto tensioner provided with a friction member pressed against the outer peripheral surface of
One end side of the elastic body extending in the arc shape is locked to the other of the fixing member and the rotating member, and the other end side is a free end,
A damping member is provided that extends in an arc shape between the coil spring and the elastic body, and presses the friction member against the outer peripheral surface of the pressure-receiving cylindrical portion via the elastic body due to the reduced diameter of the coil spring. An auto tensioner characterized by that.   Protruding part to the outer diameter side is provided on one end side of the elastic body, and a bent part in the axial direction is provided on the end part of the coil spring on the side locked to the other of the fixing member and the rotating member. The auto tensioner according to claim 1, wherein the protruding portion of the elastic body is sandwiched and locked by a bent portion of the coil spring, the other of the fixing member and the rotating member.   The damping member is configured to contact the coil spring within one turn of the spiral coil from an end portion on the side where the coil spring is locked to the other of the fixing member and the rotating member. 2. The auto tensioner according to 2.   The auto tensioner according to any one of claims 1 to 3, wherein the damping member is provided with a convex portion projecting to the outer diameter side, and the convex portion is fitted into a concave portion provided on the other of the fixing member and the rotating member. .

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